C# と VB.NET の質問掲示板

お世話になります。
VB2005でEXCEL2000にﾃﾞｰﾀを出力しています。
winXPSP2で実行するとプロセスが開放されません。しかし、Windws2003ｻｰﾊﾞｰで実行するとプロセスが開放されます。
色々なサイトで皆さんが飽き飽きしたネタだと思いますが、何がおかしいかご教授下さい。

Dim xlApplication As Excel.Application = Nothing
' COM オブジェクトの解放を保証するために Try 〜 Finally を使用する
Try
    xlApplication = New Excel.Application()
    ' 警告メッセージなどを表示しないようにする
    xlApplication.DisplayAlerts = False
    Dim xlBooks As Excel.Workbooks = xlApplication.Workbooks
    Try
        ' 既存の Excel ブックを開く
         Dim xlBook As Excel.Workbook = xlBooks.Open(wsPath)
         Try
            Dim xlSheets As Excel.Sheets = xlBook.Worksheets
            Try
                Dim xlSheet As Excel.Worksheet = DirectCast(xlSheets(1), Excel.Worksheet)
                Try
                    Dim xlCells As Excel.Range = xlSheet.Cells
                    Try
                        'ｼｰﾄの再計算を中止(処理高速化のため）
                        xlSheet.EnableCalculation = False
                        Dim xlRange As Excel.Range = DirectCast(xlCells(3, 2), Excel.Range)
                        Dim xlBorders As Excel.Borders
                        Try
                            xlRange.Value = deCargoDate.Text
                        Finally
                            If Not xlRange Is Nothing Then
                                Dim iRemainCount As Integer = System.Runtime.InteropServices.Marshal.ReleaseComObject(xlRange)
                                If iRemainCount <> 0 Then
                                    MessageBox.Show("参照カウントの残り(xlRange) == " & iRemainCount.ToString())
                                End If
                                xlRange = Nothing
                            End If
                        End Try
                         '編集
                        For mrow As Integer = 0 To dt.Rows.Count - 1
                            For mcol As Integer = 0 To dt.Columns.Count - 2
                                xlRange = DirectCast(xlCells(mrow + 6, mcol + 2), Excel.Range)
                                xlBorders = DirectCast(xlRange.Borders, Excel.Borders)
                                Try
                                    xlBorders.LineStyle = Excel.XlLineStyle.xlContinuous
                                    xlRange.Value = dt.Rows(mrow).Item(mcol)
                                Finally
                                    If Not xlBorders Is Nothing Then
                                        Dim iRemainCount As Integer = System.Runtime.InteropServices.Marshal.ReleaseComObject(xlBorders)
                                        If iRemainCount <> 0 Then
                                            MessageBox.Show("参照カウントの残り(xlBorders) == " & iRemainCount.ToString())
                                        End If
                                        xlBorders = Nothing
                                    End If
                                    If Not xlRange Is Nothing Then
                                        Dim iRemainCount As Integer = System.Runtime.InteropServices.Marshal.ReleaseComObject(xlRange)
                                        If iRemainCount < 0 Then
                                            MessageBox.Show("参照カウントの残り(xlRange) == " & iRemainCount.ToString())
                                        End If
                                        xlRange = Nothing
                                    End If
                                End Try
                            Next
                        Next
                        ''ｼｰﾄの再計算を再開
                        xlSheet.EnableCalculation = True
                        xlBook.SaveAs(wsNewPath)
                   Finally
                        If Not xlCells Is Nothing Then
                            Dim iRemainCount As Integer = System.Runtime.InteropServices.Marshal.ReleaseComObject(xlCells)
                            MessageBox.Show("参照カウントの残り(xlCells) == " & iRemainCount.ToString())
                            xlCells = Nothing
                        End If
                    End Try
                Finally
                    If Not xlSheet Is Nothing Then
                        Dim iRemainCount As Integer = System.Runtime.InteropServices.Marshal.ReleaseComObject(xlSheet)
                        MessageBox.Show("参照カウントの残り(xlSheet) == " & iRemainCount.ToString())
                        xlSheet = Nothing
                    End If
                End Try
           Finally
                If Not xlSheets Is Nothing Then
                    Dim iRemainCount As Integer = System.Runtime.InteropServices.Marshal.ReleaseComObject(xlSheets)
                    MessageBox.Show("参照カウントの残り(xlSheets) == " & iRemainCount.ToString())
                    xlSheets = Nothing
                End If
            End Try
        Finally
            If Not xlBook Is Nothing Then
                Try
                    xlBook.Close()
                Finally
                    Dim iRemainCount As Integer = System.Runtime.InteropServices.Marshal.ReleaseComObject(xlBook)
                    MessageBox.Show("参照カウントの残り(xlBook) == " & iRemainCount.ToString())
                    xlBook = Nothing
                End Try
           End If
       End Try
    Finally
        If Not xlBooks Is Nothing Then
            Dim iRemainCount As Integer = System.Runtime.InteropServices.Marshal.ReleaseComObject(xlBooks)
            MessageBox.Show("参照カウントの残り(xlBooks) == " & iRemainCount.ToString())
            xlBooks = Nothing
       End If
    End Try
Finally
    If Not xlApplication Is Nothing Then
        Try
            xlApplication.Quit()
        Finally
            Dim iRemainCount As Integer = System.Runtime.InteropServices.Marshal.ReleaseComObject(xlApplication)
            MessageBox.Show("参照カウントの残り(xlApplication) == " & iRemainCount.ToString())
            xlApplication = Nothing
        End Try
    End If
End Try

参照カウントの残りはすべてゼロです。
以上、宜しくお願い致します。

お世話になります。
おてやわらか様のご指摘通りに1つずつ確認しているのですが、
EXCELをオープンしてCLOSEするだけで、EXCELプロセスが消えません。
何がおかしいか、ご教授願えませんでしょうか？
Dim xlApplication As Excel.Application = Nothing
' COM オブジェクトの解放を保証するために Try 〜 Finally を使用する
Try
    xlApplication = New Excel.Application()
    ' 警告メッセージなどを表示しないようにする
    xlApplication.DisplayAlerts = False
    Dim xlBooks As Excel.Workbooks = xlApplication.Workbooks
    Try
        ' 既存の Excel ブックを開く
         Dim xlBook As Excel.Workbook = xlBooks.Open(wsPath)
         Try

         'この間はコメントアウトしています。

         Finally
            If Not xlBook Is Nothing Then
                Try
                    xlBook.Close()
                Finally
                    Dim iRemainCount As Integer = System.Runtime.InteropServices.Marshal.ReleaseComObject(xlBook)
                    MessageBox.Show("参照カウントの残り(xlBook) == " & iRemainCount.ToString())
                    xlBook = Nothing
                End Try
           End If
       End Try
    Finally
        If Not xlBooks Is Nothing Then
            Dim iRemainCount As Integer = System.Runtime.InteropServices.Marshal.ReleaseComObject(xlBooks)
            MessageBox.Show("参照カウントの残り(xlBooks) == " & iRemainCount.ToString())
            xlBooks = Nothing
       End If
    End Try
Finally
    If Not xlApplication Is Nothing Then
        Try
            xlApplication.Quit()
        Finally
            Dim iRemainCount As Integer = System.Runtime.InteropServices.Marshal.ReleaseComObject(xlApplication)
            MessageBox.Show("参照カウントの残り(xlApplication) == " & iRemainCount.ToString())
            xlApplication = Nothing
        End Try
    End If
End Try